Liquid discharge head

Abstract

A liquid discharge head includes: first and second common channels extending in a first direction; and individual channels including pressure chambers and nozzles. Each of the individual channels includes: a supply portion; a descender portion extending in a second direction; and a return portion extending in a third direction. The return portion includes: a throttle portion; and a wide portion. Each of the nozzles overlaps with the wide portion. A relationship of L2>L1 is satisfied, wherein L1 is a distance in the third direction from a center of each of the nozzles to a throttle starting position, and L2 is a distance in the third direction passing through a center in a cross section of the descender portion and ranging from a center line parallel to the second direction to the center of each of the nozzles.

What is claimed is: 
     
       1. A liquid discharge head, comprising:
 a first common channel extending in a first direction; 
 a second common channel extending in the first direction; and 
 a plurality of individual channels including a plurality of pressure chambers arranged in the first direction and a plurality of nozzles arranged in the first direction, each of the individual channels including:
 a supply portion that causes the first common channel to communicate with one of the pressure chambers; 
 a descender portion extending in a second direction that intersects with the first direction and causing one of the pressure chambers positioned at an upstream side in the second direction to communicate with one of the nozzles positioned at a downstream side in the second direction; and 
 a return portion branching from the descender portion and extending in a third direction, which intersects with the first direction and the second direction, to communicate with the second common channel, the return portion including: a throttle portion and a wide portion, 
 
 wherein a downstream end of the throttle portion in the third direction is connected to the second common channel, 
 wherein an upstream end of the wide portion in the third direction is connected to the descender portion and a downstream end of the wide portion in the third direction is connected to the throttle portion, 
 wherein a cross-sectional area in a plane perpendicular to the third direction of the wide portion is larger than that of the throttle portion, 
 wherein each of the nozzles is located downstream of the upstream end of the wide portion in the third direction, each of the nozzles is located upstream of the downstream end of the wide portion in the third direction, and each of the nozzles overlaps in the second direction with the wide portion, and 
 wherein a relationship of
     L 2> L 1>0 
 
 
       is satisfied, wherein L 1  is a distance in the third direction from a center of each of the nozzles to a throttle starting position that is a connection position between the throttle portion and the wide portion, and L 2  is a distance in the third direction from a center line of the descender portion to the center of each of the nozzles, wherein the center line of the descender portion passes through a center in a cross section orthogonal to the second direction of the descender portion and is parallel to the second direction. 
     
     
       2. The liquid discharge head according to  claim 1 , wherein a relationship of
     L 2>2× L 1
 
 is satisfied. 
 
     
     
       3. The liquid discharge head according to  claim 1 , wherein a relationship of
     W> 30× V  
 
 is satisfied, wherein W is a flow velocity of a liquid along the third direction at an upstream position in the second direction from the center of each of the nozzles, and V is a flow velocity of the liquid along the second direction at the upstream position in the second direction from the center of each of the nozzles. 
 
     
     
       4. The liquid discharge head according to  claim 1 , wherein, in the throttle starting position, an end surface at the upstream side in the second direction of the wide portion is flush with an end surface at the upstream side in the second direction of the throttle portion. 
     
     
       5. The liquid discharge head according to  claim 1 , wherein a relationship of
     D 1< L 1 
 is satisfied, wherein D 1  is a distance in the third direction from an end surface at a downstream side in the third direction of the descender portion to each of the nozzles. 
 
     
     
       6. The liquid discharge head according to  claim 1 , wherein an end surface at a downstream side in the third direction of the descender portion is positioned at an upstream side in the third direction from each of the nozzles. 
     
     
       7. The liquid discharge head according to  claim 1 , wherein a relationship of
     H 1≥ H 2
 
 is satisfied, wherein H 1  is a length in the second direction from an end surface at the downstream side in the second direction of the wide portion to an end surface at the upstream side in the second direction of the wide portion, and H 2  is a length in the second direction from an end surface at the downstream side in the second direction of the throttle portion to an end surface at the upstream side in the second direction of the throttle portion. 
 
     
     
       8. The liquid discharge head according to  claim 1 , wherein a relationship of
   Φ> H 1− H 2
 
 is satisfied, wherein Φ is an inner diameter of each of the nozzles, H 1  is a length in the second direction from an end surface at the downstream side in the second direction of the wide portion to an end surface at the upstream side in the second direction of the wide portion, and H 2  is a length in the second direction from an end surface at the downstream side in the second direction of the throttle portion to an end surface at the upstream side in the second direction of the throttle portion. 
 
     
     
       9. The liquid discharge head according to  claim 1 , wherein a downstream end of the descender portion in the second direction and the return portion are positioned at the downstream side in the second direction than both ends of the one of the pressure chambers in the second direction.